Question

Of the following gases, ________ will have the greatest rate of effusion at a given temperature. Of the following gases, ________ will have the greatest rate of effusion at a given temperature. NH3 HCl CH4 Ar HBr

Answer 1

Answer: From the given gases, the greatest rate of effusion is of $CH_4$

Explanation:

Rate of effusion of a gas is determined by a law known as Graham's Law.

This law states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of the molar mass of the gas. The equation given by this law follows:

$\text{Rate of diffusion}\propto \frac{1}{\sqrt{\text{Molar mass of the gas}}}$

It is visible that molar mass is inversely related to rate of effusion. So, the gas having lowest molar mass will have the highest rate of effusion.

For the given gases:

Molar mass of $NH_3=17g/mol$

Molar mass of $HCl=36.5g/mol$

Molar mass of $CH_4=16g/mol$

Molar mass of $Ar=40g/mol$

Molar mass of $HBr=81g/mol$

The molar mass of methane gas is the lowest. Thus, it will have the greatest rate of effusion.

Hence, the greatest rate of effusion is of $CH_4$